Hello @Jesse Peltola,
Thank you for posting your query on Microsoft Q&A.
It seems that you were unable to log in to your work or school account (Microsoft 365 Business) because you couldn't complete the second-factor authentication. Based on your statement, I understand that you are the only global administrator in your Azure tenant.
So is there any possibility that the school email abolishment affect the Microsoft Authenticator activity?
If you are removing your school email account from Microsoft Authenticator app will not have any impact on your work or school user account.
If you have one account with admin role and if you are blocked entirely, you can reach out to our support team. You can look into below article to get support numbers depending on your country.
or creating a ticket through a different account: https://learn.microsoft.com/en-us/microsoft-365/admin/get-help-support?view=o365-worldwide#phone-support
Create a ticket with Microsoft support team. Give them the tenant ID which is locked out in your description. Tell them that no admin account has access anymore and your partners also have no access anymore.
Once you create a ticket with support team you will have to work with our data protection team. You will have to first prove your identity against your tenant for security purpose. Post that this team will help you with help you in getting access to your tenant or unlock your account depending on your scenario.
Also, for the future, you can create an emergency access account (break glass) in Azure AD. This account will help prevent being accidentally locked out of your Azure Active Directory (Azure AD) organization because you can't sign in for any reason.
https://docs.microsoft.com/en-us/azure/active-directory/roles/security-emergency-access
I hope this information is helpful. Please feel free to reach out if you have any further questions.
Thanks,
Raja Pothuraju.
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